1. Field of the Invention
This invention relates to optical microscopes.
2. Discussion of the Related Art
One important tool for biological research and medical diagnostics is the optical microscope. FIG. 1 shows a conventional optical microscope 10. The optical microscope 10 includes an objective lens 12 and an imaging lens 14, i.e., an eyepiece. Exemplary microscopes include objective and imaging lenses 12, 14 that are compound lenses or lens systems.
Both objective and imaging lenses 12, 14 contribute to image magnification. The objective lens 12 forms a first magnified image 16 of an object 18 being examined. The first image 16 becomes the object for the imaging lens 14, which produces a further magnified final image 20. Here, the final image 20 is virtual and observed by an observer""s eye 22. The total image magnification is the product of the separate magnifications produced by the objective lens 12 and the imaging lens 14.
Use of an optical microscope to examine internal tissues of a large animal typically entails removing the tissues from the animal. The removal facilitates positioning the microscope""s objective lens for viewing the tissues. Thus, microscopic examination is typically performed in-vitro, i.e., outside the animal""s body.
Various embodiments provide optical microscopes useable for in-vivo examinations of biological tissues and other samples.
In one aspect, the invention features an optical microscope that includes a compound GRIN objective and a lens system. The compound GRIN objective is able to form an image of an object that is located near one end of the GRIN objective. The compound GRIN objective is configured to limit the lateral field of view for imaging to a distance equal to the diameter of the GRIN objective. The lens system is positioned to form a magnified image of the image formed by the compound GRIN objective.
In another aspect, the invention features an optical microscope that includes a lens system and a GRIN objective. The GRIN objective is positioned to produce an image that the lens system is capable of magnifying. The GRIN objective includes a first and second GRIN lenses, which are end-coupled. The first and second GRIN lenses have respective pitches P1 and P2, and P2 is greater than P1. The first GRIN lens has a length that belongs to the interval (0, xc2xcP1] modulo a whole- or half-integer times P1.